Alapakkam Sampath, Ph.D.

A Short Biography:

Alapakkam P. (Sam) Sampath is a Professor of Ophthalmology and Neurobiology at UCLA, and the Associate Director of the Jules Stein Eye Institute.  After completing his Ph.D. in 1999 in physiology at UCLA, he did postdoctoral fellowships at Stanford and the University of Washington before joining USC as an Assistant Professor in 2005.  He moved his laboratory to UCLA in 2013.  Sam is the Principal Investigator on several NIH grants to study how the retina encodes light entering the eye in both health and disease.  Over the past decade his laboratory has led efforts to determine how the retina encodes visual information under very dim light, or for night vision.  During this time his lab has identified the biological mechanisms that allow our high visual sensitivity, and how these mechanisms malfunction in night blindness.  Sam is the recipient of the Karl Kirschgessner Junior Faculty Award and received a Scholar Award from the McKnight Endowment Fund for Neuroscience.  His current research remains focused on how the photoreceptor cells, the rods and cones, are activated by light and how these signals are processed in the retinal circuity.

Work Titles
UCLA Professor, Brain Research Institute Professor, Stein Eye Institute Member, Molecular, Cellular & Integrative Physiology GPB Home Area Member, Neuroscience GPB Home Area

Contact Information:

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Laboratory Address:

Jules Stein A-200


A selected list of publications:

Fain Gordon, Sampath Alapakkam P   Rod and cone interactions in the retina F1000Research, 2018; 7: .
Sarria Ignacio, Cao Yan, Wang Yuchen, Ingram Norianne T, Orlandi Cesare, Kamasawa Naomi, Kolesnikov Alexander V, Pahlberg Johan, Kefalov Vladimir J, Sampath Alapakkam P, Martemyanov Kirill A   LRIT1 Modulates Adaptive Changes in Synaptic Communication of Cone Photoreceptors Cell reports, 2018; 22(13): 3562-3573.
Martemyanov Kirill A, Sampath Alapakkam P   The Transduction Cascade in Retinal ON-Bipolar Cells: Signal Processing and Disease Annual review of vision science, 2017; 3(13): 25-51.
Pahlberg Johan, Frederiksen Rikard, Pollock Gabriel E, Miyagishima Kiyoharu J, Sampath Alapakkam P, Cornwall M Carter   Voltage-sensitive conductances increase the sensitivity of rod photoresponses following pigment bleaching The Journal of physiology, 2017; 595(11): 3459-3469.
Field Greg D, Sampath Alapakkam P   Behavioural and physiological limits to vision in mammals Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 2017; 372(1717): 3459-3469.
Wang Yuchen, Fehlhaber Katherine E, Sarria Ignacio, Cao Yan, Ingram Norianne T, Guerrero-Given Debbie, Throesch Ben, Baldwin Kristin, Kamasawa Naomi, Ohtsuka Toshihisa, Sampath Alapakkam P, Martemyanov Kirill A   The Auxiliary Calcium Channel Subunit α2δ4 Is Required for Axonal Elaboration, Synaptic Transmission, and Wiring of Rod Photoreceptors Neuron, 2017; 93(6): 1359-1374.e6.
Ingram Norianne T, Sampath Alapakkam P, Fain Gordon L   Why are rods more sensitive than cones? The Journal of physiology, 2016; 594(19): 5415-26.
Cho Alice, Ratliff Charles, Sampath Alapakkam, Weiland James   Changes in ganglion cell physiology during retinal degeneration influence excitability by prosthetic electrodes Journal of neural engineering, 2016; 13(2): 025001.
Cao Yan, Sarria Ignacio, Fehlhaber Katherine E, Kamasawa Naomi, Orlandi Cesare, James Kiely N, Hazen Jennifer L, Gardner Matthew R, Farzan Michael, Lee Amy, Baker Sheila, Baldwin Kristin, Sampath Alapakkam P, Martemyanov Kirill A   Mechanism for Selective Synaptic Wiring of Rod Photoreceptors into the Retinal Circuitry and Its Role in Vision Neuron, 2015; 87(6): 1248-1260.
Majumder Anurima, Pahlberg Johan, Muradov Hakim, Boyd Kimberly K, Sampath Alapakkam P, Artemyev Nikolai O   Exchange of Cone for Rod Phosphodiesterase 6 Catalytic Subunits in Rod Photoreceptors Mimics in Part Features of Light Adaptation The Journal of neuroscience : the official journal of the Society for Neuroscience, 2015; 35(24): 9225-35.
Sarria Ignacio, Pahlberg Johan, Cao Yan, Kolesnikov Alexander V, Kefalov Vladimir J, Sampath Alapakkam P, Martemyanov Kirill A   Sensitivity and kinetics of signal transmission at the first visual synapse differentially impact visually-guided behavior eLife, 2015; 4(24): e06358.
Majumder Anurima, Pahlberg Johan, Boyd Kimberly K, Kerov Vasily, Kolandaivelu Saravanan, Ramamurthy Visvanathan, Sampath Alapakkam P, Artemyev Nikolai O   Transducin translocation contributes to rod survival and enhances synaptic transmission from rods to rod bipolar cells Proceedings of the National Academy of Sciences of the United States of America, 2013; 110(30): 12468-73.
Chen Shih-Kuo, Chew Kylie S, McNeill David S, Keeley Patrick W, Ecker Jennifer L, Mao Buqing Q, Pahlberg Johan, Kim Bright, Lee Sammy C S, Fox Michael A, Guido William, Wong Kwoon Y, Sampath Alapakkam P, Reese Benjamin E, Kuruvilla Rejji, Hattar Samer   Apoptosis regulates ipRGC spacing necessary for rods and cones to drive circadian photoentrainment Neuron, 2013; 77(3): 503-15.
Mao Wen, Miyagishima K J, Yao Yun, Soreghan Brian, Sampath Alapakkam P, Chen Jeannie   Functional comparison of rod and cone Gα(t) on the regulation of light sensitivity The Journal of biological chemistry, 2013; 288(8): 5257-67.
Arman A Cyrus, Sampath Alapakkam P   Dark-adapted response threshold of OFF ganglion cells is not set by OFF bipolar cells in the mouse retina Journal of neurophysiology, 2012; 107(10): 2649-59.
Cho Alice K, Sampath Alapakkam P, Weiland James D   Physiological response of normal and RD mouse retinal ganglion cells to electrical stimulation Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference, 2012; 2012(10): 2985-8.
Cao Yan, Pahlberg Johan, Sarria Ignacio, Kamasawa Naomi, Sampath Alapakkam P, Martemyanov Kirill A   Regulators of G protein signaling RGS7 and RGS11 determine the onset of the light response in ON bipolar neurons Proceedings of the National Academy of Sciences of the United States of America, 2012; 109(20): 7905-10.
Doroudchi M Mehdi, Greenberg Kenneth P, Liu Jianwen, Silka Kimberly A, Boyden Edward S, Lockridge Jennifer A, Arman A Cyrus, Janani Ramesh, Boye Shannon E, Boye Sanford L, Gordon Gabriel M, Matteo Benjamin C, Sampath Alapakkam P, Hauswirth William W, Horsager Alan   Virally delivered channelrhodopsin-2 safely and effectively restores visual function in multiple mouse models of blindness Molecular therapy : the journal of the American Society of Gene Therapy, 2011; 19(7): 1220-9.
Pahlberg Johan, Sampath Alapakkam P   Visual threshold is set by linear and nonlinear mechanisms in the retina that mitigate noise: how neural circuits in the retina improve the signal-to-noise ratio of the single-photon response BioEssays : news and reviews in molecular, cellular and developmental biology, 2011; 33(6): 438-47.
Okawa Haruhisa, Pahlberg Johan, Rieke Fred, Birnbaumer Lutz, Sampath Alapakkam P   Coordinated control of sensitivity by two splice variants of Gα(o) in retinal ON bipolar cells The Journal of general physiology, 2010; 136(4): 443-54.
Altimus Cara M, Güler Ali D, Alam Nazia M, Arman A Cyrus, Prusky Glen T, Sampath Alapakkam P, Hattar Samer   Rod photoreceptors drive circadian photoentrainment across a wide range of light intensities Nature neuroscience, 2010; 13(9): 1107-12.
Okawa Haruhisa, Miyagishima K Joshua, Arman A Cyrus, Hurley James B, Field Greg D, Sampath Alapakkam P   Optimal processing of photoreceptor signals is required to maximize behavioural sensitivity The Journal of physiology, 2010; 588(Pt 11): 1947-60.
Matthews Hugh R, Sampath Alapakkam P   Photopigment quenching is Ca2+ dependent and controls response duration in salamander L-cone photoreceptors The Journal of general physiology, 2010; 135(4): 355-66.
Miyagishima Kiyoharu J, Cornwall M Carter, Sampath Alapakkam P   Metabolic constraints on the recovery of sensitivity after visual pigment bleaching in retinal rods The Journal of general physiology, 2009; 134(3): 165-75.

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